1. Field of the Invention
The present invention relates to the art of welding with wire-feeders and improved heat dissipation on a contactor used in welding systems with wire-feeders.
2. Background
Modern wire-feeders in welding systems employ an electromechanical switch known as a “contactor” to electrically connect a welding gun to its power supply at the appropriate time. For the welding gun to operate, the contactor (or switch) is closed as the operator depresses the trigger of the welding gun. That is, pulling the trigger on the gun causes a solenoid in the contactor to move a bridge that brings the welding gun in electrical connection with the welding power source. Because of the high currents used in welding, arcs form in the contactor as the solenoid opens and closes the electrical circuit. Over time these arcs erode the metal at the point of electrical contact, resulting in increased resistance within the contactor. This increased resistance is the primary cause of heat dissipation problems and overall contactor degradation—ultimately resulting in device failure for the contactor.
In practice, the solution to contactor degradation has been to make the contactor inexpensive and easy to replace. This solution, however, cannot avoid the problems caused when a contactor fails in the middle of a weld process. Depending on the weld, a contactor failure during the middle of a weld may force the partially welded pieces to be scrapped. Accordingly, a contactor with a longer lifetime before failure is desired. Contactors, however, are price sensitive products where inexpensive improvements extending the life of contactors are highly desired. For example, solid state contactors last longer than electromechanical contactors, but are not used as widely because they cost significantly more than electromechanical contactors.
Over the lifetime of an electromechanical contactor, the internal resistance increases as a result of the arcing that occurs when the contactor is switched on and off. This resistance impedes current flow, reduces the voltage supplied to the welding gun, and creates significant heating problems. Because of the high currents passing through the contactor, the heating problems often lead to device failure. As such, an economical solution for improving heat dissipation is needed in the market.